WDXS31 PGTW 070900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY)     
WARNING NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.4S 117.0E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 502 NM NORTH-NORTHEAST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 11S HAS CONTINUED TO RAPIDLY INTENSIFY (RI),
BRIEFLY FLIRTING WITH AN EYE, AND HAS INTENSIFIED 40 KNOTS OVER THE
PAST DAY. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
CENTRAL DENSE OVERCAST OBSCURING THE LOW-LEVEL CIRCULATION CENTER,
HOWEVER, A PARTIAL 070620Z AMSR2 89GHZ MICROWAVE IMAGE REVEALS
SPIRAL BANDING OVER THE WESTERN SEMICIRCLE WITH A COMPACT EYEWALL
SURROUNDING A SMALL MICROWAVE EYE FEATURE. CONSEQUENTLY, THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE. ENVIRONMENTAL
CONDITIONS REMAIN HIGHLY FAVORABLE SUPPORTING THE RI PHASE. THE
INITIAL INTENSITY OF 75 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED
ON THE PGTW AND APRF DVORAK ESTIMATES. ADT AND SATCON ESTIMATES ARE
TOO LOW, HOWEVER, THE MOST RECENT OPEN-AIIR ESTIMATE OF 65 KNOTS
APPEARS MORE REASONABLE CONSIDERING THE COMPACT STRUCTURE AND
INCIPIENT EYE. THIS COMPACT STRUCTURE IS EVIDENT IN THE SMALL
34-KNOT WIND RADII, WHICH ARE BASED ON A DETAILED ANALYSIS OF THE
070156Z ASCAT-C WINDSPEED IMAGE.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T5.0 - 90 KTS
   APRF: T4.5 - 77 KTS
   CIMSS SATCON: 59 KTS AT 070510Z
   CIMSS ADT: 59 KTS AT 070530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TC 11S IS EXPECTED TO TRACK GENERALLY WESTWARD
ALONG THE NORTHERN PERIPHERY OF THE STR THROUGH THE FORECAST
PERIOD. A SERIES OF FAST-MOVING MIDLATITUDE SHORTWAVE TROUGHS ARE
EXPECTED TO PROPAGATE TO THE SOUTH BUT WILL NOT SIGNIFICANTLY
IMPACT OR WEAKEN THE STR UNTIL AFTER TAU 120 WHEN A MAJOR SHORTWAVE
TROUGH APPROACHES AND DEEPENS TO THE SOUTHWEST. TC 11S WILL PEAK AT
110 KNOTS BY TAU 24 AND WILL THEN WEAKEN BRIEFLY BEFORE
REINTENSIFYING NEAR TAU 72. THIS SHORT DURATION WEAKENING PHASE IS
ASSOCIATED WITH A PERIOD OF INCREASING UPPER-LEVEL EASTERLIES AND
HIGHER VERTICAL WIND SHEAR AS WELL AS DRY AIR ENTRAINMENT AS
INDICATED IN GFS AND ALL THE RELIABLE INTENSITY GUIDANCE.          

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, THE DETERMINISTIC
MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72 WITH A 60NM
SPREAD IN SOLUTIONS AT TAU 72. PROBABILISTIC GUIDANCE SUPPORTS A
GENERALLY WESTWARD TRACK BUT SHOWS A LARGER SPREAD OF SOLUTIONS.
AFTER TAU 72, BOTH THE DETERMINISTIC AND PROBABILISTIC GUIDANCE
DIVERGES REFLECTING INCREASING UNCERTAINTY IN THE JTWC FORECAST
TRACK. THE 070000Z COAMPS-TC ENSEMBLE, WHICH EXCELS AT IDENTIFYING
RI, INDICATES 60 TO 80 PERCENT PROBABILITIES SUPPORTING SUSTAINED
INTENSIFICATION OVER THE NEXT 24 TO 30 HOURS. LENDING FURTHER
SUPPORT TO THIS SUSTAINED RI PERIOD, RAPID INTENSIFICATION GUIDANCE
HAS TRIGGERED. ALTHOUGH THE COAMPS-TC RI PROBABILITIES DECREASE
FROM TAU 30 TO TAU 66, THERE IS AN INCREASE TO 20 TO 30 PERCENT
PROBABILITY IN THE DAY 3 TO DAY 4 TIMEFRAME, WHICH SUPPORTS THE
CURRENT JTWC INTENSITY FORECAST PHILOSOPHY.  

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
NNNN